Which ecosystems have clear boundaries. Ecological system: concept, essence, types and levels

Back in the Middle Ages, it was noticed that the life expectancy of city dwellers was shorter than that of rural residents. The lack of greenery, narrow streets, small courtyards, where sunlight practically did not penetrate, created unfavorable conditions for human life.

Varied factors, associated with the growth of cities, to one degree or another affect the formation of a person, his health. This forces scientists to more and more seriously study the influence of the environment on city residents. It turns out that the person’s mood and ability to work depend on the conditions in which a person lives, the height of the ceilings in his apartment and how sound-permeable its walls are, how a person gets to his place of work, with whom he communicates on a daily basis, and how the people around him treat each other. , activity and his whole life.

A person comes up with thousands of tricks in order to make his life in cities more convenient: hot water, telephone, various types of transport, roads, services and entertainment. However, in big cities the disadvantages of urban life are especially pronounced: housing and transport problems, increased morbidity level. The latter is to a certain extent explained by the simultaneous impact on the body of two, three or more factors, each of which has a minor negative effect, but in the aggregate their impact leads to serious consequences.

For example, saturation of the environment and production with high-speed and high-speed machines increases stress and requires additional effort from a person, which leads to overwork. It is well known that an overtired person suffers more from air pollution, infections, etc.

Polluted air in the city, poisoning the blood with carbon monoxide, causes the same harm to a non-smoker as smoking a pack of cigarettes a day by a smoker. A serious negative factor in modern cities is the so-called “noise pollution”.

To reduce the negative impact on residents, the urban landscape should not be a monotonous “stony desert”. In city architecture, one should strive for a harmonious combination of social (buildings, roads, transport, communications) and biological aspects (green areas, parks, public gardens). Landscape architects can play a big role in this.

A modern city should be considered as an ecosystem in which the most favorable conditions for human life are created. Consequently, it should not only be comfortable housing, transport, a diverse range of services, but also favorable for life and health human habitat is clean air, a pleasing urban landscape, green corners where everyone can relax in silence, admiring the beauty of nature.

Considering the ability of green spaces to favorably influence the state of the environment, they need to be brought as close as possible to the place where people live, work, study and relax.

Preservation and special planting of trees and shrubs, creation of lawns and flower beds are an integral part of a set of measures to protect and transform the environment. Green spaces not only create favorable microclimatic and sanitary conditions, but also increase the artistic expressiveness of architectural ensembles.

Protective green zones should occupy a special place around industrial enterprises and highways. It is recommended to plant trees and shrubs that are resistant to pollution, for example, American maple, Canadian poplar, cordate linden, Cossack and Virginia juniper, white willow, brittle buckthorn, pedunculate oak, and red elderberry.

When placing green spaces, it is necessary to observe the principle of uniformity and continuity. Gardens, parks, public gardens, and intra-city boulevards should be combined both with each other and with plantings located outside the city. This will ensure the supply of fresh country air to all residential areas of the city. The most important components of the city’s greening system are plantings in residential neighborhoods, on the sites of child care institutions, schools, sports complexes, etc.

By caring for green spaces, protecting and increasing them, every city resident can make their own contribution to improving the city’s ecology.

It is no coincidence that ecologists believe that in a modern city a person should not be cut off from nature, but, as it were, dissolved in it. Therefore, the total area of ​​green spaces in cities should occupy more than half of its territory.

Biotic community, or biocenosis.Ecosystem . Biogeocenosis. Biosphere. Artificial, or anthropogenic, ecosystems. Agrobiocenosis.

1. What biocenoses and ecosystems do you know?
2. What is the difference between a biocenosis and an ecosystem?
3. What abiotic factors influence the flora and fauna of a community?
4. What ecosystems are called anthropogenic?
5. What is the difference between natural and anthropogenic ecosystems?
6. Why is it believed that in rural areas living conditions for people are, as a rule, more favorable than in large cities?
7. Is it possible to create a favorable living environment for humans in large cities?

Make a description of any biogeocenosis (familiar to you from excursions). Indicate what plants and animals can live here.

Biological community ( biocenosis ) is a collection of individuals of different species living in a certain territory and interacting with each other. Examples of communities are coniferous forests, steppes, tropical rainforests, coral reefs, deserts. A biological community together with its habitat is called an ecosystem ( biogeocenosis ).

The physical properties of the environment, especially the annual regime of temperature and precipitation, influence the characteristics of the biological community and determine the occurrence of either forest, grassland, desert or swamp. The biological community, in turn, can also change the physical characteristics of the environment. In terrestrial ecosystems, for example, wind speed, humidity, temperature and soil characteristics can be influenced by the plants and animals that live there.

Within the biogeocenosis, each species occupies its own ecological niche (a unique set of resources). Most often, niches for species arise at a certain stage of succession. succession – the process of gradual transformation of species composition, community structure and physical characteristics of the environment that occurs following natural or anthropogenic disturbances in an ecosystem.

Some species can only be observed at certain stages of succession. For example, sun-loving butterflies and annual plants are often found only in the early stages of succession, in the first months after the formation of a “bald patch” in an old forest. Shade-tolerant forest plants and birds that nest in the hollows of dead trees appear in the later stages of succession, i.e. in the old forest. Human economic activity often disrupts the natural order of succession.

The composition of communities is also determined by competition and predators. Predators often significantly reduce the number of species - their prey - and can even displace some of them from their usual habitats. When predators are exterminated, the population of their prey can increase to or even exceed critical levels. Then, after the limiting resource is exhausted, the destruction of the population may begin.

Community structure is also determined by symbiotic relationships (including mutualistic ones), in which species are in mutually beneficial relationships. Mutualistic species achieve higher densities when living together. Common examples of such mutualism are plants with fleshy fruits and birds that feed on these fruits and spread their seeds; fungi and algae, which together form lichens; plants that provide shelter to ants, supplying them with nutrients; coral polyps and algae living in them.

"Introduction to general biology and ecology. Grade 9." A.A. Kamensky (GDZ)

Characteristics of communities, ecosystems (biogeocenoses)

Question 1. Which of the communities and ecosystems you know have more or less clear boundaries?
Community- a group of plants, or a group of animals, for example, forest plants or pond animals. Biogeocenosis has relatively clear boundaries. Biogeocenosis is a complex of living beings (biocenosis) and an abiotic environment, which includes the territory occupied by organisms. Biogeocenosis and ecosystem are similar concepts, but not identical. The concept of ecosystem is broader than the concept of biogeocenosis. An ecosystem can be represented by a pond, a swamp, a puddle, an anthill, a mountain range and, finally, the biosphere as a whole. Biogeocenosis is an ecosystem, the boundaries of which are determined by the plant community - phytocenosis (oak forests, steppes, coniferous forests, etc.), that is biogeocenosis- this is a special case ecosystems.
Particularly clear boundaries are characteristic of artificial cenoses - agrocenoses (rice field, rye field, forest belt, etc.).

Question 2. Can all bird populations inhabiting a forest be considered a community?
Biocenosis- this is a complex of living beings inhabiting a forest area, i.e. the totality of populations of all plants, animals, fungi and microorganisms living on the territory of a given forest area. The variety of bird species inhabiting the forest area represents only a small part of the animals living in a given forest area.

Question 3. What factors of inanimate nature influence the flora and fauna of the community?
The flora and fauna of a community are influenced by factors of inanimate nature: light, temperature, humidity, chemical composition of water and soil, atmosphere, etc.

An ecosystem includes all living organisms (plants, animals, fungi and microorganisms) that, to one degree or another, interact with each other and the inanimate environment around them (climate, soil, sunlight, air, atmosphere, water, etc. .).

An ecosystem does not have a specific size. It can be as big as a desert or a lake, or as small as a tree or a puddle. Water, temperature, plants, animals, air, light and soil all interact together.

The essence of the ecosystem

In an ecosystem, each organism has its own place or role.

Consider the ecosystem of a small lake. In it, you can find all types of living organisms, from microscopic to animals and plants. They depend on things such as water, sunlight, air, and even the amount of nutrients in the water. (Click to learn more about the five basic needs of living organisms).

Lake ecosystem diagram

Any time a “stranger” (a living creature(s) or an external factor such as rising temperatures) is introduced into an ecosystem, catastrophic consequences can occur. This occurs because the new organism (or factor) is capable of distorting the natural balance of interactions and causing potential harm or destruction to the non-native ecosystem.

Typically, the biotic members of an ecosystem, together with their abiotic factors, depend on each other. This means the absence of one member or one abiotic factor can affect the entire ecological system.

If there is not enough light and water, or if the soil contains few nutrients, the plants may die. If plants die, the animals that depend on them are also at risk. If animals that depend on plants die, then other animals that depend on them will also die. The ecosystem in nature works the same way. All its parts must function together to maintain balance!

Unfortunately, ecosystems can be destroyed by natural disasters such as fires, floods, hurricanes and volcanic eruptions. Human activity is also contributing to the destruction of many ecosystems and.

Main types of ecosystems

Ecological systems have indefinite dimensions. They are able to exist in a small space, for example under a stone, a rotting tree stump or in a small lake, and also occupy large areas (like the entire tropical forest). From a technical point of view, our planet can be called one huge ecosystem.

Diagram of a small ecosystem of a rotting stump

Types of ecosystems depending on scale:

• Microecosystem- a small-scale ecosystem, such as a pond, puddle, tree stump, etc.
• Mesoecosystem- an ecosystem, such as a forest or a large lake.
• Biome. A very large ecosystem or collection of ecosystems with similar biotic and abiotic factors, such as an entire tropical forest with millions of animals and trees, and many different water bodies.

The boundaries of ecosystems are not marked by clear lines. They are often separated by geographical barriers such as deserts, mountains, oceans, lakes and rivers. Because boundaries are not strictly defined, ecosystems tend to merge with each other. This is why a lake can have many small ecosystems with their own unique characteristics. Scientists call this mixing "Ecotone".

Types of ecosystems by type of occurrence:

In addition to the above types of ecosystems, there is also a division into natural and artificial ecological systems. A natural ecosystem is created by nature (forest, lake, steppe, etc.), and an artificial one is created by man (garden, personal plot, park, field, etc.).

Ecosystem types

There are two main types of ecosystems: aquatic and terrestrial. Every other ecosystem in the world falls into one of these two categories.

Terrestrial ecosystems

Terrestrial ecosystems can be found anywhere in the world and are divided into:

Forest ecosystems

These are ecosystems that have an abundance of vegetation or a large number of organisms living in a relatively small space. Thus, in forest ecosystems the density of living organisms is quite high. A small change in this ecosystem can affect its entire balance. Also, in such ecosystems you can find a huge number of fauna representatives. In addition, forest ecosystems are divided into:

• Tropical evergreen forests or tropical rain forests:, receiving an average rainfall of more than 2000 mm per year. They are characterized by dense vegetation, dominated by tall trees located at different heights. These areas are a refuge for various species of animals.
• Tropical deciduous forests: Along with a huge variety of tree species, shrubs are also found here. This type of forest is found in quite a few corners of the planet and is home to a wide variety of flora and fauna.
• : They have a fairly small number of trees. Evergreen trees predominate here, renewing their foliage throughout the year.
• Broadleaf forests: They are located in humid temperate regions that receive sufficient rainfall. During the winter months, trees shed their leaves.
• : Located directly in front of, the taiga is defined by evergreen coniferous trees, sub-zero temperatures for half the year and acidic soils. In the warm season, you can find a large number of migratory birds, insects and.

desert ecosystem

Desert ecosystems are located in desert areas and receive less than 250 mm of rainfall per year. They occupy about 17% of the Earth's total land area. Due to extremely high air temperatures, poor access to and intense sunlight, and are not as rich as other ecosystems.

Meadow ecosystem

Grasslands are located in tropical and temperate regions of the world. The meadow area mainly consists of grasses, with a small number of trees and shrubs. The meadows are inhabited by grazing animals, insectivores and herbivores. There are two main types of meadow ecosystems:

• : Tropical grasslands that have a dry season and are characterized by individually growing trees. They provide food for a large number of herbivores and are also hunting grounds for many predators.
• Prairies (temperate grasslands): This is an area with moderate grass cover, completely devoid of large shrubs and trees. The prairies contain forbs and tall grasses and experience arid climate conditions.
• Steppe meadows: Areas of dry grasslands that are located near semi-arid deserts. The vegetation of these grasslands is shorter than that of savannas and prairies. Trees are rare and are usually found on the banks of rivers and streams.

Mountain ecosystems

The mountainous terrain provides a diverse range of habitats where a large number of animals and plants can be found. At altitude, harsh climatic conditions usually prevail in which only alpine plants can survive. Animals that live high in the mountains have thick coats to protect them from the cold. The lower slopes are usually covered with coniferous forests.

Aquatic ecosystems

Aquatic ecosystem - an ecosystem located in an aquatic environment (for example, rivers, lakes, seas and oceans). It includes aquatic flora, fauna, and water properties, and is divided into two types: marine and freshwater ecological systems.

Marine ecosystems

They are the largest ecosystems, covering about 71% of the Earth's surface and containing 97% of the planet's water. Sea water contains large amounts of dissolved minerals and salts. The marine ecological system is divided into:

• Oceanic (a relatively shallow part of the ocean that is located on the continental shelf);
• Profundal zone (deep-sea area not penetrated by sunlight);
• Benthal region (area inhabited by bottom organisms);
• Intertidal zone (the place between low and high tides);
• Estuaries;
• Coral reefs;
• Salt marshes;
• Hydrothermal vents where chemosynthesizers form the food supply.

Many species of organisms live in marine ecosystems, namely: brown algae, corals, cephalopods, echinoderms, dinoflagellates, sharks, etc.

Freshwater ecosystems

Unlike marine ecosystems, freshwater ecosystems cover only 0.8% of the Earth's surface and contain 0.009% of the world's total water reserves. There are three main types of freshwater ecosystems:

• Still water: water where there is no current, such as swimming pools, lakes or ponds.
• Flowing: Fast moving waters such as streams and rivers.
• Wetlands: Places where the soil is constantly or periodically flooded.

Freshwater ecosystems are home to reptiles, amphibians and about 41% of the world's fish species. Fast-moving waters typically contain higher concentrations of dissolved oxygen, thereby supporting greater biodiversity than the stagnant waters of ponds or lakes.

Ecosystem structure, components and factors

An ecosystem is defined as a natural functional ecological unit consisting of living organisms (biocenosis) and their inanimate environment (abiotic or physicochemical), which interact with each other and create a stable system. Pond, lake, desert, pastures, meadows, forests, etc. are common examples of ecosystems.

Each ecosystem consists of abiotic and biotic components:

Ecosystem structure

Abiotic components

Abiotic components are unrelated factors of life or the physical environment that influence the structure, distribution, behavior and interactions of living organisms.

Abiotic components are mainly represented by two types:

• Climatic factors, which include rain, temperature, light, wind, humidity, etc.
• Edaphic factors, including soil acidity, topography, mineralization, etc.

The importance of abiotic components

The atmosphere provides living organisms with carbon dioxide (for photosynthesis) and oxygen (for respiration). The processes of evaporation and transpiration occur between the atmosphere and the Earth's surface.

Solar radiation heats the atmosphere and evaporates water. Light is also necessary for photosynthesis. provides plants with energy for growth and metabolism, as well as organic products to feed other life forms.

Most living tissue consists of a high percentage of water, up to 90% or more. Few cells are able to survive if the water content drops below 10%, and most die when the water content is less than 30-50%.

Water is the medium through which mineral food products enter plants. It is also necessary for photosynthesis. Plants and animals receive water from the surface of the Earth and soil. The main source of water is precipitation.

Biotic components

Living things, including plants, animals and microorganisms (bacteria and fungi), present in an ecosystem are biotic components.

Based on their role in the ecological system, biotic components can be divided into three main groups:

• Producers produce organic substances from inorganic ones using solar energy;
• Consumers feed on ready-made organic substances produced by producers (herbivores, predators, etc.);
• Decomposers. Bacteria and fungi that destroy dead organic compounds of producers (plants) and consumers (animals) for nutrition, and release into the environment simple substances (inorganic and organic) formed as by-products of their metabolism.

These simple substances are repeatedly produced through cyclic metabolism between the biotic community and the abiotic environment of the ecosystem.

Ecosystem levels

To understand the levels of an ecosystem, consider the following figure:

Ecosystem Level Diagram

Individual

An individual is any living creature or organism. Individuals do not breed with individuals from other groups. Animals, as opposed to plants, are usually classified under this concept, since some members of the flora can interbreed with other species.

In the above diagram, you can see that the goldfish interacts with its environment and will breed exclusively with members of its own species.

Population

Population is a group of individuals of a given species that live in a specific geographic area at a given time. (An example would be the goldfish and its species). Please note that a population includes individuals of the same species, which may have various genetic differences such as coat/eye/skin color and body size.

Community

A community includes all living organisms in a certain area at a given time. It may contain populations of living organisms of different species. In the diagram above, notice how goldfish, salmonids, crabs and jellyfish coexist in a certain environment. A large community usually includes biodiversity.

Ecosystem

An ecosystem includes communities of living organisms that interact with their environment. At this level, living organisms depend on other abiotic factors such as rocks, water, air and temperature.

Biome

In simple words, it is a collection of ecosystems that have similar characteristics with their abiotic factors adapted to the environment.

Biosphere

When we consider different biomes, each one leading into another, a huge community of people, animals and plants is formed, living in certain habitats. is the totality of all ecosystems present on Earth.

Food chain and energy in the ecosystem

All living things must eat to obtain the energy needed to grow, move, and reproduce. But what do these living organisms eat? Plants get their energy from the Sun, some animals eat plants and others eat animals. This feeding relationship in an ecosystem is called a food chain. Food chains typically represent the sequence of who eats whom in a biological community.

Below are some living organisms that can fit into the food chain:

Food chain diagram

A food chain is not the same thing as . The trophic network is a collection of many food chains and is a complex structure.

Energy transfer

Energy is transferred through food chains from one level to another. Some of the energy is used for growth, reproduction, movement and other needs, and is not available for the next level.

Shorter food chains store more energy than longer ones. The energy expended is absorbed by the environment.